$.equals

by Andrea Ercolino

HTML

<p>a paragraph</p>
<div>a div with <span>a span</span> inside</div>

JavaScript

$.equals = function( a, b, options ) {

    options = $.extend({

        // if true, in case of inequality, a trace of the first difference is logged to the console
        verbose: false,

        // use 'strict' for ===, 'abstract' for ==
        comparison: 'strict',

        // if true, an item is compared, otherwise it is ignored
        // receives a value and a key, returns true or false
        filter: function () {
            return true;
        }

    }, options || {});

    var initial_step = false;
    if (typeof options.trace == 'undefined') {
        initial_step = true;
        options.trace = [];
    }

    if (options.comparison == 'strict' ? a === b : a == b) {
        return true;
    }

    var a_type = $.type(a);
    var b_type = $.type(b);
    if (! (a_type == b_type)) {
        log(['types', a_type, b_type, a, b]);
        return false;
    }

    var a_keys = decompose(a, options.filter).keys;
    var b_keys = decompose(b, options.filter).keys;

    var a_length = a_keys.length;
    var b_length = b_keys.length;
    if (! (a_length == b_length)) {
        log(['lengths', a_length, b_length, a, b]);
        return false;
    }

    var length = a_length; // == b_length
    if (length == 0) { // a and b are scalars
        return a === b;
    }

    // compare corresponding elements
    for (var i = 0; i < length; i++) {
        var key = a_keys[i];
        var a_value = a[key];
        var b_value = b[key];
        var equal = $.equals( a_value, b_value, options );
        if (! equal) {
            log(['values at key "' + key + '"', a_value, b_value, a, b]);
            return false;
        }
    }

    if (initial_step) {
        log(['values', null, null, a, b]);
    }
    return true;

    //---

    // returns true if the given object is a scalar (not in JavaScript terms, though...)
    function isScalarValue(object) {
        return object === null || /undefined|boolean|number|string/.test(typeof object);
    }

    // returns a...